This invention relates to mobile vehicles such as excavators, cranes and the like, and, more particularly to an improved counterweight arrangement for such vehicles.
The booms and power hoist equipment of excavators, cranes, and the like are often mounted on a carrier vehicle, such as a crawler type carrier or a pneumatic tired truck chassis, to afford an easily transportable unit. The boom is generally supported at its foot upon one end of a machinery platform which also mounts the power hoist equipment, and such platform is in turn supported on a turntable so that the boom may be rotated for reach in any direction relative to the supporting chassis. It is necessary to counterbalance the boom and load carried thereby and this is accomplished in part by placing the power hoist equipment at an opposite end of the machinery platform remote from the boom with the turntable supporting the platform at some intermediate point. This, however, will provide only a partial counterbalancing of a boom with a large reach and it is necessary to provide a massive counterweight which generally is supported at the opposite end of the machinery platform.
It is the common practice to mount the counterweight in a manner which permits the removal of the counterweight to enhance the moveability of such vehicles. It is most desirable that the counterweight be capable of removal with a minimum of time and effort so that the down time of the units occasioned by the removal is small. However, when the excavator, crane, or the like, is in operation the counterweight must be positively supported upon the platform and secured against swinging or swaying. Further, the mobile vehicle may be the only hoisting equipment available at a particular site so that separate hoisting equipment should not be necessary to remove the counterweight from the platform.
It has heretofore been proposed to mount a counterweight to the rear end of a crane or excavator and to utilize the boom hoist mechanism to raise and lower the counterweight. Examples of such devices are disclosed in U.S. Pat. Nos. 2,689,655, 3,251,479 and 3,278,045. It has also been heretofore proposed to utilize a cable extending between the boom of a crane or the bucket of a tractor and the counterweight to raise and lower the counterweight. Examples of such devices are disclosed in U.S. Pat. Nos. 3,135,404 and 3,726,416.
The present invention is directed to an improved counterweight arrangement which is simpler in construction, less costly to manufacture and more reliable in operation than the heretofore utilized arrangements to raise and lower counterweights.